Tumor necrosis factor alpha (TNF-α) is a cytokine that is released primarily by mononuclear phagocytes in response to immunostimulators. TNF-α is capable of enhancing most cellular processes, such as differentiation, recruitment, proliferation, and proteolytic degradation. At low levels, TNF-α confers protection against infective agents, tumors, and tissue damage. However, TNF-α also has a role in many diseases. When administered to a patient, TNF-α causes or aggravates inflammation, fever, cardiovascular effects, hemorrhage, coagulation, and acute phase responses similar to those seen during acute infections and shock states. Enhanced or unregulated TNF-α production has been implicated in a number of diseases and medical conditions, for example, cancers, such as solid tumors and blood-borne tumors; heart disease, such as congestive heart failure; and viral, genetic, inflammatory, allergic, and autoimmune diseases.
Adenosine 3′,5′-cyclic monophosphate (cAMP) also plays a role in many diseases and conditions, such as, but not limited to, asthma and inflammation, and other conditions (Lowe and Cheng, Drugs of the Future, 17(9), 799-807, 1992). It has been shown that the elevation of cAMP in inflammatory leukocytes inhibits their activation and the subsequent release of inflammatory mediators, including TNF-α and NF-κB. Increased levels of cAMP also leads to the relaxation of airway smooth muscle.
It is believed that the primary cellular mechanism for the inactivation of cAMP is the breakdown of cAMP by a family of isoenzymes referred to as cyclic nucleotide phosphodiesterases (PDE) (Beavo and Reitsnyder, Trends in Pharm., 11, 150-155, 1990). There are eleven known PDE families. It is recognized, for example, that the inhibition of PDE type IV is particularly effective in both the inhibition of inflammatory mediator release and the relaxation of airway smooth muscle (Verghese, et al., J. Pharm. Exper. Therapeut., 272(3), 1313-1320, 1995). Thus, compounds that inhibit PDE4 (PDE IV) specifically, may inhibit inflammation and aid the relaxation of airway smooth muscle with a minimum of unwanted side effects, such as cardiovascular or anti-platelet effects. Currently used PDE4 inhibitors lack the selective action at acceptable therapeutic doses.
Cancer is a particularly devastating disease, and increases in blood TNF-α levels are implicated in the risk of and the spreading of cancer. Normally, in healthy subjects, cancer cells fail to survive in the circulatory system, one of the reasons being that the lining of blood vessels acts as a barrier to tumor-cell extravasation. However, increased levels of cytokines have been shown to substantially increase the adhesion of cancer cells to endothelium in vitro. One explanation is that cytokines, such as TNF-α, stimulate the biosynthesis and expression of a cell surface receptors called ELAM-1 (endothelial leukocyte adhesion molecule). ELAM-1 is a member of a family of calcium-dependent cell adhesion receptors, known as LEC-CAMs, which includes LECAM-1 and GMP-140. During an inflammatory response, ELAM-1 on endothelial cells functions as a “homing receptor” for leukocytes. Recently, ELAM-1 on endothelial cells was shown to mediate the increased adhesion of colon cancer cells to endothelium treated with cytokines (Rice et al., 1989, Science 246:1303-1306).
Inflammatory diseases such as arthritis, related arthritic conditions (e.g., osteoarthritis and rheumatoid arthritis), inflammatory bowel disease (e.g., Crohn's disease and ulcerative colitis), sepsis, psoriasis, atopic dermatitis, contact dermatitis, chronic obstructive pulmonary disease, and chronic inflammatory pulmonary diseases are also prevalent and problematic ailments. TNF-α plays a central role in the inflammatory response and the administration of their antagonists block chronic and acute responses in animal models of inflammatory disease.
Enhanced or unregulated TNF-α production has been implicated in viral, genetic, inflammatory, allergic, and autoimmune diseases. Examples of such diseases include but are not limited to: HIV; hepatitis; adult respiratory distress syndrome; bone-resorption diseases; chronic obstructive pulmonary diseases; chronic pulmonary inflammatory diseases; asthma; dermatitis; cystic fibrosis; septic shock; sepsis; endotoxic shock; hemodynamic shock; sepsis syndrome; post ischemic reperfusion injury; meningitis; psoriasis; fibrotic disease; cachexia; graft rejection; auto-immune disease; rheumatoid spondylitis; arthritic conditions, such as rheumatoid arthritis and osteoarthritis; osteoporosis; Crohn's disease; ulcerative colitis; inflammatory-bowel disease; multiple sclerosis; systemic lupus erythrematosus; ENL in leprosy; radiation damage; asthma; and hyperoxic alveolar injury. Tracey et al., 1987, Nature 330:662-664 and Hinshaw et al., 1990, Circ. Shock 30:279-292 (endotoxic shock); Dezube et al., 1990, Lancet, 335:662 (cachexia); Millar et al., 1989, Lancet 2:712-714 and Ferrai-Baliviera et al., 1989, Arch. Surg. 124:1400-1405 (adult respiratory distress syndrome); Bertolini et al., 1986, Nature 319:516-518, Johnson et al., 1989, Endocrinology 124:1424-1427, Holler et al., 1990, Blood 75:1011-1016, and Grau et al., 1989, N. Engl. J. Med. 320:1586-1591 (bone resorption diseases); Pignet et al., 1990, Nature, 344:245-247, Bissonnette et al., 1989, Inflammation 13:329-339 and Baughman et al., 1990, J. Lab. Clin. Med. 115:36-42 (chronic pulmonary inflammatory diseases); Elliot et al., 1995, Int. J. Pharmac. 17:141-145 (rheumatoid arthritis); von Dullemen et al., 1995, Gastroenterology, 109:129-135 (Crohn's disease); Duh et al., 1989, Proc. Nat. Acad. Sci. 86:5974-5978, Poll et al., 1990, Proc. Nat. Acad. Sci. 87:782-785, Monto et al., 1990, Blood 79:2670, Clouse et al., 1989, J. Immunol. 142, 431-438, Poll et al., 1992, AIDS Res. Hum. Retrovirus, 191-197, Poli et al. 1990, Proc. Natl. Acad. Sci. 87:782-784, Folks et al., 1989, PNAS 86:2365-2368 (HIV and opportunistic infections resulting from HIV).
Pharmaceutical compounds that can block the activity or inhibit the production of certain cytokines, including TNF-α, may be beneficial therapeutics. Many small-molecule inhibitors have demonstrated an ability to treat or prevent inflammatory diseases implicated by TNF-α (for a review, see Lowe, 1998 Exp. Opin. Ther. Patents 8:1309-1332). One such class of molecules are the substituted phenethylsulfones described in U.S. Pat. No. 6,020,358.
The preparation and selection of a solid form of a pharmaceutical compound is complex, given that a change in solid form may affect a variety of physical and chemical properties, which may provide benefits or drawbacks in processing, formulation, stability and bioavailability, among other important pharmaceutical characteristics. Potential pharmaceutical solids include crystalline solids and amorphous solids. Amorphous solids are characterized by a lack of long-range structural order, whereas crystalline solids are characterized by structural periodicity. The desired class of pharmaceutical solid depends upon the specific application; amorphous solids are sometimes selected on the basis of e.g., an enhanced dissolution profile, while crystalline solids may be desirable for properties such as, e.g., physical or chemical stability (see, e.g., S. R. Vippagunta et al., Adv. Drug. Deliv. Rev., (2001) 48:3-26; L. Yu, Adv. Drug. Deliv. Rev., (2001) 48:27-42).
Whether crystalline or amorphous, potential solid forms of a pharmaceutical compound include single-component and multiple-component solids. Single-component solids consist essentially of the pharmaceutical compound in the absence of other compounds. Variety among single-component crystalline materials may potentially arise, e.g., from the phenomenon of polymorphism, wherein multiple three-dimensional arrangements exist for a particular pharmaceutical compound (see, e.g., S. R. Byrn et al., Solid State Chemistry of Drugs, (1999) SSCI, West Lafayette). The importance of studying polymorphs was underscored by the case of Ritonavir, an HIV protease inhibitor that was formulated as soft gelatin capsules. About two years after the product was launched, the unanticipated precipitation of a new, less soluble polymorph in the formulation necessitated the withdrawal of the product from the market until a more consistent formulation could be developed (see S. R. Chemburkar et al., Org. Process Res. Dev., (2000) 4:413-417).
Additional diversity among the potential solid forms of a pharmaceutical compound may arise, e.g., from the possibility of multiple-component solids. Crystalline solids comprising two or more ionic species may be termed salts (see, e.g., Handbook of Pharmaceutical Salts Properties, Selection and Use, P. H. Stahl and C. G. Wermuth, Eds., (2002), Wiley, Weinheim). Additional types of multiple-component solids that may potentially offer other property improvements for a pharmaceutical compound or salt thereof include, e.g., hydrates, solvates, co-crystals and clathrates, among others (see, e.g., S. R. Byrn et al., Solid State Chemistry of Drugs, (1999) SSCI, West Lafayette). Moreover, multiple-component crystal forms may potentially be susceptible to polymorphism, wherein a given multiple-component composition may exist in more than one three-dimensional crystalline arrangement. The preparation of solid forms is of great importance in the development of a safe, effective, stable and marketable pharmaceutical compound.
Provided herein are embodiments addressing a need for solid forms of the compound chemically named (+)-2-[1-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4-acetylaminoisoindoline-1,3-dione (“Compound A”), which was disclosed in U.S. application Ser. No. 10/392,195, filed Mar. 19, 2003 (issued as U.S. Pat. No. 6,962,940), as well as U.S. Provisional Application Ser. Nos. 60/366,515, filed Mar. 20, 2002 and 60/438,450, filed Jan. 7, 2003.